donkeys

Preliminary investigation into relationships between donkey and horse skull morphology and brain morphology

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Date presented: 
Thursday 23 November 2017
Abstract

All horses and donkeys belong to the genus Equus but anatomical and behavioural differences exist among species. Equus caballus displays distinctive conformational attributes among breeds provisionally related to ganglion cell distribution and skull and brain morphology. Equus asinus shows less variation in skull shape, and little is known about brain organisation. The current research compared skull and brain morphology between horses and donkeys. Skulls of Equus caballus, primarily of Standardbred type (N=14) and Equus asinus (N=16), were obtained postmortem. All animals had been humanely euthanised for reasons unrelated to this study. Heads were sectioned sagitally along the midline and photographed for measurement of various skull structures using Image J software. Measurements included: skull index (SI)=zygomatic width*100/skull length; cranial index (CI)=cranial width*100/cranial length; nasal index (NI)=zygomatic width*100/nasal length; cranial profile index (CPI)=rectangular area bordered by an 80mm line from orbital notch and occiput; nasal profile index (NPI)= rectangular area bordered by 80mm line from orbital notch and tip of nasal bone; olfactory lobe area (OLA); OL pitch [angle between hard palate and the OL axis]; brain pitch [angle between longitudinal axis of the cerebral hemispheres and the hard palate]; and whorl location (WL) [distance of OL from the level of the forehead whorl]. A General Linear Model determined the main effect of species with Sidak’s multiple comparisons of species’ differences among the various measurements. Donkeys had shorter heads (cranial lengths) than horses (19.7±2.5 vs 23.6±1.4cm respectively; F1,23=51.49, P<0.0002). Donkeys also had smaller cranial widths (13±3.4cm; F1,17=15.91, P<0.001) and mandibular depths (24±2.6cm; F1,21=13.05, P<0.002) than horses (19±0.8 and 27.2±1.1cm, respectively). There was no species difference in SI, ZI, or NI (P>0.40), but donkeys tended to have a smaller CI than horses (F1,17=3.59, P<0.08). Similarly, donkeys had a smaller CPI than horses (F1,21=7.54, P<0.034), but there was no difference in NPI (F1,21=0.05, P>0.83). Donkeys also had a smaller OLA than horses (1.4±0.3 vs 2.3±1.3cm2 respectively; F1,13=4.96, P<0.05) although there was no difference in brain pitch (F1,23=0.69, P>0.43). The greatest difference was seen in WL, which corresponded to the level of the OL in horses, but was extremely rostral in donkeys (F1,21=24.29, P<0.0001). These results show clear differentiation in skull morphology between horses and donkeys which may be linked to behaviour. This may be useful in validating different approaches in the training and management of horses versus donkeys.

Lay person message: Horses demonstrate specific behaviours which may be associated with skull shape, although nothing is known about this relationship in donkeys. This pilot study has shown that donkeys have smaller brain cases and olfactory lobes than Standardbred horses. Donkeys’ facial whorls are located lower down the face while horses’ are in close proximity to the brain’s olfactory lobe. Clarifying differences between horses and donkeys is crucial to understanding species-specific behavioural responses and providing appropriate management and training practices.

Owner awareness of the importance of equine dentistry and its role in preventing welfare problems

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Date presented: 
Thursday 5 October 2017
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Recent clinical and post-mortem studies have documented dental disease as a major but often unrecognized, disorder of equids, including horses and donkeys. A study to investigate the prevalence of oral and dental disorders was performed, in two endangered breeds of donkeys: the Mirandês Donkey and the Zamorano-Leonés Donkey, through a prospective cross-sectional study of 800 donkeys, divided in to 7 age groups (ranging 0–34 years).
Cheek teeth disorders were present in 82.8% of study donkeys, ranging from a prevalence of 29.6% in the <2.5 years old group to 100% in the >25 years old group. In addition 74% of donkeys suffered from incisor disorders, ranging from 56.8% in the youngest group to 90.3% in donkeys >25 years.
The study evaluated socio-economic data from individual owners (n=341), owning 86% of the study population (n=688 donkeys), including age, profession, level of education and previous knowledge of dentistry. Results highlighted their advanced age (65.3 years), and the extremely high percentage of owners without previous knowledge of donkey dentistry (97.1%) (331/341). Previous knowledge of dentistry was mentioned only by 2.9% of owners (10/341), mainly by owners with a higher level of education, with 80% (8/10) having 12 years of education or more. However, only two owners had provided previous treatment to their donkeys. It is important to mention that even these two owners had other animals without treatment, meaning that animals were treated when presenting with clinical signs of oral and dental disease and were not treated on a prophylactic basis.
This study highlights the importance of educational programmes focused on the prophylactic importance of donkey dentistry, especially when comparing prevalence of dental disorders in working donkeys and previous knowledge on dentistry.

Influence of dental correction in nociceptive tests response, fecal appearance, body condition score and apparent dry matter digestibility of Zamorano-Leonés donkeys (Equus asinus)

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J. B. Rodrigues, L. M. Ferreira, E. Bastos, F. San Roman, C. Viegas, A. S. Santos. July 2013. Influence of dental correction in nociceptive tests response, fecal appearance, body condition score and apparent dry matter digestibility of Zamorano-Leonés donkeys (Equus asinus). Journal of Animal Science. 91. 4765-4771.

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Publication date: 
1 July 2013
Volume: 
91
Page numbers: 
4765-4771
DOI number: 
10.2527/jas.2013-6311
Abstract

The influence of dental correction on nociceptive (pressure) test responses, fecal appearance, BCS, and apparent digestibility coefficient for DM was studied in 18 Zamorano-Leonés donkeys, an endangered local breed from the Zamora province in Spain. For this purpose, donkeys were divided into 2 homogeneous control and treatment groups, based on age, BCS, and dental findings. On d 1, 45, 90, and 135, BCS and nociceptive test responses were evaluated in all donkeys. Feed and fecal samples were collected from all donkeys for 3 consecutive days, starting at each of the aforementioned days. Apparent digestibility coefficient for DM was estimated, using ADL as an internal marker. A progressive decrease of positive nociceptive test responses was observed from d 1 up to 90 (P < 0.01) in the treatment group. No difference between groups was observed for BCS. However, BCS at d 90 was greater (P = 0.018) than observed on d 1 or 45, indicating a time influence. Concerning apparent digestibility coefficient for DM, there were differences among collection days in apparent digestibility coefficient for DM (P < 0.05). No differences in fecal appearance were observed between treatments or collection days. This study highlighted the importance of regular dental care for not only Zamorano-Leonés donkeys but also the equid population, in general, to improve their welfare.

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The effectiveness of faecal removal methods of pasture management to control the cyathostomin burden of donkeys

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Christopher J Corbett, Sandy Love, Anna Moore, Faith A. Burden, Jacqui. B. Matthews, Matthew Denwood. January 2014. The effectiveness of faecal removal methods of pasture management to control the cyathostomin burden of donkeys. Parasites and Vectors. 7:48.

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Publication date: 
24 January 2014
Volume: 
7
Issue: 
48
DOI number: 
doi:10.1186/1756-3305-7-48
Abstract

Background: The level of anthelmintic resistance within some cyathostomin parasite populations has increased to the level where sole reliance on anthelmintic-based control protocols is not possible. Management-based nematode control methods, including removal of faeces from pasture, are widely recommended for use in association with a reduction in anthelmintic use to reduce selection pressure for drug resistance; however, very little work has been performed to quantitatively assess the effectiveness of such methods.

Methods: We analysed data obtained from 345 donkeys at The Donkey Sanctuary (Devon, UK), managed under three different pasture management techniques, to investigate the effectiveness of faeces removal in strongyle control in equids. The management groups were as follows: no removal of faeces from pasture, manual, twice weekly removal of faeces from pasture and automatic, twice-weekly removal of faeces from pasture (using a mechanical pasture sweeper). From turn-out onto pasture in May, monthly faecal egg counts were obtained for each donkey and the dataset subjected to an auto regressive moving average model.

Results: There was little to no difference in faecal egg counts between the two methods of faecal removal; both resulted in significantly improved cyathostomin control compared to the results obtained from the donkeys that grazed pasture from which there was no faecal removal.

Conclusions: This study represents a valuable and unique assessment of the effectiveness of the removal of equine faeces from pasture, and provides an evidence base from which to advocate twice-weekly removal of faeces from pasture as an adjunct for equid nematode control. Widespread adoption of this practice could substantially reduce anthelmintic usage, and hence reduce selection pressure for nematode resistance to the currently effective anthelmintic products.

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